Internal combustion engine systems conventionally include a starting system to start the engine and a generator system to charge the battery and power the electrical system once the engine is running. In conventional starting systems, an electric starter motor is mounted to the engine and includes a drive pinion that, in operation (e.g., by activating a key-operated switch), meshes with a ring gear on a flywheel of the engine. The drive pinion on the starter motor rotates the flywheel so as to initiate the engine's operation. In some systems, an overrunning or freewheel clutch is installed between the starter output shaft and the drive pinion. The overrunning clutch is configured to disengage the connection between the starter output shaft and the drive pinion as soon as the flywheel of the engine is turning faster than the drive pinion of the starter motor. In order to generate sufficient torque to turn the flywheel, starting systems utilize a high gear ratio (e.g., 10:1-20:1) between the engine and the starter motor.
As noted above, internal combustion engine systems also conventionally include a generator system to charge the battery and power the electrical system once the engine is running. In conventional generator systems, a crankshaft pulley is coupled to the crankshaft of the engine. A belt is coupled to the crankshaft pulley and to one or more accessories, including an alternator or generator. The alternator is configured to convert mechanical energy received via the belt to electrical energy. The electrical energy may be transferred to a battery to power the electrical system of the vehicle. Generator systems conventionally utilize a gear ratio of approximately 2:1-5:1 between the alternator and the engine. Accordingly, the gear ratio utilized in generator systems is lower than the gear ratio utilized in starting systems.